There is no standard for the layout of the four arithmetic operations, the decimal point, equal sign or other more advanced mathematical functions on the keypad of a calculator. The modern four-row arrangement debuted with the Sundstrand Adding Machine in 1911. The calculator had the digit keys arranged in one row, with zero on the left, and 9 on the right. A smaller, 10-key input first started on the Standard Adding Machine in 1901. The first key-activated mechanical calculators and many cash registers used "parallel" keys with one column of 0 to 9 for each position the machine could use. In 1984, the first projected capacitance keypad was used to sense through the shop window of a travel agency. Keypads for the entry of PINs and for product selection appear on many devices including ATMs, vending machines, Point of Sale payment devices, time clocks, combination locks and digital door locks. Separate external plug-in keypads can be purchased. Many laptop computers have special function keys that turn part of the alphabetical keyboard into a numerical keypad as there is insufficient space to allow a separate keypad to be built into the laptop's chassis. This number pad (commonly abbreviated to numpad) is usually positioned on the right side of the keyboard because most people are right-handed. A computer keyboard usually has a small numeric keypad on the side, in addition to the other number keys on the top, but with a calculator-style arrangement of buttons that allow more efficient entry of numerical data.
0 kommentar(er)
